U.S Pat. No. 4,899,523 to Frumholtz et al discloses a mower having a frame, a tongue pivotally connected to the frame near the center thereof, and a disc cutterbar carried by the frame. The disc cutterbar includes a plurality of individual cutting units arranged side-by-side transversely of the frame. A main drive shaft connected to a power-take-off shaft on a tractor extends through the tongue to an upper input gearbox on the mower frame, and distribution shafts extend outwardly from a lower input gearbox to output gearboxes located adjacent outer ends of the cutterbar. The distribution shafts drive the cutting units located at the outer ends of the cutterbar while the intermediate cutting units are driven by the end cutting units.
A drawback of the mower disclosed in the Frumholtz et al patent is that power from the tractor is transmitted over a relatively long distance through the main drive shaft, the upper and lower input gearboxes, the distribution shafts, and the output gearboxes to the cutterbar. The Frumholtz et al mower has another drawback in that it utilizes four gearboxes (i.e. two input gearboxes and two output gearboxes) in order to drive the cutterbar.